Propulsion flow path duct systems and methods

ABSTRACT

A flow path duct system for a propulsion system of an aircraft includes a base defining a flow surface. The base has an internal surface and an external surface. A plurality of perforations are formed through the base between the internal surface and the external surface. A plurality of supports define a plurality of cavities. The plurality of supports extend outwardly from the external surface of the of the base. One or more of the plurality of cavities are in fluid communication with the one or more of the plurality of perforations. A backing surface is secured to the plurality of supports. The plurality of supports are disposed between the base and the backing surface. The one or more of the plurality of cavities are in fluid communication with an internal volume defined by the internal surface of the base through the one or more of the plurality of perforations. The base, the plurality of supports, and the backing surface can be integrally formed together as a monolithic, load-bearing structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/321,591, entitled “Propulsion Flow Path Duct Systems and Methods,”filed May 17, 2021, which is hereby incorporated by reference in itsentirety, and which, in turn, claims priority benefits from U.S.Provisional Patent Application No. 63/074,658, entitled “IntegratedPropulsion Flow Path System and Method for Reduced Noise,” filed Sep. 4,2020, and both applications are incorporated by reference in theirentirety.

FIELD OF THE DISCLOSURE

Embodiments of the subject disclosure relate to acoustical dampingsystems and methods, such as additively manufactured, integral acousticdamping systems and methods within a propulsion flow path duct of anaircraft.

BACKGROUND OF THE DISCLOSURE

Various air vehicles include propulsion systems that generate noise. Oncommercial aircraft, for example, engine nacelle inlets include fanblades and other components that generate noise. To reduce the generatednoise, acoustic liners have been installed in such areas to dampen thesound. For example, known liners include porous or mesh face sheets,typically made of titanium, stainless steel, or aluminum, laid over aircavities with a rigid backing. In some applications, the air cavitiesform a honeycomb structure to provide some rigidity to the liners. Someapplications can include two air cavities, separated by a mesh material.In general, the liners act as damping and phase cancellation mechanismsfor noise.

However, the known liners are typically mounted to primary structure andadd complexity to the overall design.

SUMMARY OF THE DISCLOSURE

A need exists for a system and method for efficiently and effectivelyreducing noise in relation to various components, such as withinpropulsion systems of aircraft. Further, a need exists for a lesscomplex system and method for reducing noise with respect to engine ofaircraft, for example.

With those needs in mind, certain embodiments of the subject disclosureprovide a flow path duct system for a propulsion system of an aircraft.The flow path duct system includes a base defining a flow surface. Thebase has an internal surface and an external surface. A plurality ofperforations are formed through the base between the internal surfaceand the external surface. A plurality of supports define a plurality ofcavities. The plurality of supports extend outwardly from the externalsurface of the of the base. One or more of the plurality of cavities arein fluid communication with one or more of the plurality ofperforations. A backing surface is secured to the plurality of supports.The plurality of supports are disposed between the base and the backingsurface. The one or more of the plurality of cavities are in fluidcommunication with an internal volume defined by the internal surface ofthe base through the one or more of the plurality of perforations.

In at least one embodiment, the base, the plurality of supports, and thebacking surface are integrally formed together as a monolithic,load-bearing structure. For example, the base, the plurality ofsupports, and the backing surface are additively manufactured together.

In at least one embodiment, each of the plurality of cavities is influid communication with at least one of the plurality of perforations.As a further example, the plurality of cavities and the plurality ofperforations cooperate to provide a plurality of Helmholtz resonators.

In at least one embodiment, the plurality of cavities are shaped as oneor more of triangles, diamonds, circles, or hexagons. In at least oneembodiment, the plurality of perforations are shaped as one or more ofellipses, circles, squares, rounded squares, diamonds, rounded diamonds,rectangles, rounded rectangles, parallelograms, or roundedparallelograms.

In at least one embodiment, the plurality of perforations define a flowsurface porosity within the base that ranges from 20% to 4%.

As an example, a depth of the plurality of cavities is the same. Asanother example, a depth of at least two of the plurality of cavities isdifferent.

In at least one embodiment, the flow path duct system includes one orboth of an inlet or an outlet nozzle having a high aspect ratio.

Certain embodiments of the subject disclosure provide a method offorming a flow path duct system for a propulsion system of an aircraft.The method includes forming a plurality of perforations through a basedefining a flow surface between an internal surface and an externalsurface; extending a plurality of supports defining a plurality ofcavities from the external surface of the of the base; fluidly couplingone or more of the plurality of cavities with one or more of theplurality of perforations, wherein said fluidly coupling comprisesfluidly coupling the one or more of the plurality of cavities with aninternal volume defined by the internal surface of the base through theone or more of the plurality of perforations; and securing a backingsurface to the plurality of supports, wherein said securing comprisesdisposing the plurality of supports between the base and the backingsurface.

Certain embodiments of the subject disclosure provide an aircraftincluding a propulsion system including a flow path duct system, asdescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective top view of an unmanned aerial vehicle,according to an embodiment of the subject disclosure.

FIG. 2 illustrates a front perspective view of an aircraft, according toan embodiment of the subject disclosure.

FIG. 3 illustrates a lateral perspective view of an engine, according toan embodiment of the subject disclosure.

FIG. 4 illustrates a perspective internal view of a flow path ductsystem, according to an embodiment of the subject disclosure.

FIG. 5 illustrates a perspective external view of a flow path ductsystem with a backing surface removed to expose supports and resultingcavities, according to an embodiment of the subject disclosure.

FIG. 6 illustrates a transverse partial cross-sectional view of a flowpath duct system having constant depth cavities, according to anembodiment of the subject disclosure.

FIG. 7 illustrates a transverse partial cross-sectional view of a flowpath duct system having constant depth cavities, according to anembodiment of the subject disclosure.

FIG. 8 illustrates transverse partial cross-sectional view of a flowpath duct system having cavities with a single step distribution indepth, or two constant depths, according to an embodiment of the subjectdisclosure.

FIG. 9 illustrates a transverse partial cross-sectional view of a flowpath duct system having cavities with a double step distribution indepth, or three constant depths, according to an embodiment of thesubject disclosure.

FIG. 10 illustrates a flow chart of a method of forming a flow path ductsystem for a propulsion system of an aircraft, according to anembodiment of the subject disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The foregoing summary, as well as the following detailed description ofcertain embodiments will be better understood when read in conjunctionwith the appended drawings. As used herein, an element or step recitedin the singular and preceded by the word “a” or “an” should beunderstood as not necessarily excluding the plural of the elements orsteps. Further, references to “one embodiment” are not intended to beinterpreted as excluding the existence of additional embodiments thatalso incorporate the recited features. Moreover, unless explicitlystated to the contrary, embodiments “comprising” or “having” an elementor a plurality of elements having a particular condition can includeadditional elements not having that condition.

In certain smaller vehicles, such as certain unmanned aerial vehicles(UAVs), or for configurations where a separate liner is not practical, asolution integral to the underlying structure is needed. As a result,there is a need for an integrated propulsion flow path in which acoustictreatments can be incorporated directly into the propulsion flow pathstructure, in contrast to be being separately secured to the structure.

Certain embodiments of the subject disclosure provide a quiet propulsionflow path duct system that includes a base having a flow surface, aplurality of supports joined together to define a plurality of cavitiesisolated from each other, and a backing surface. The supports arebetween the base and the backing surface. The base defines a pluralityof perforations. An underlying cavity is in fluid communication with aninternal volume of a duct via one or more perforations. In at least oneembodiment, the base, supports, and backing surface together form amonolithic, load bearing structure.

In at least one embodiment, instead of separately forming portions, theflow path duct system is integrally formed as a monolithic structure.For example, the flow path duct system is integrally molded and formedas a single, monolithic piece (instead of having separate componentsformed and secured together). As another example, the flow path ductsystem, including all component parts, is integrally formed throughadditive manufacturing.

In at least one embodiment, the plurality of cavities and theperforations together form a plurality of Helmholtz resonators for soundattenuation. In at least one embodiment, the plurality of cavitiesdefine a distribution of shapes including triangles, diamonds, circles,hexagons (honeycomb), or a combination thereof. Further, in at least oneembodiment, the plurality of cavities can define a distribution ofdiamond shapes. In some ducts, the perforations can be ellipses,circles, squares, rounded squares, diamonds, rounded diamonds,rectangles, rounded rectangles, parallelograms, rounded parallelograms,or a combination thereof. In at least one embodiment, the perforationscan be circles. For some embodiments, the perforations can define a flowsurface porosity. The porosity can range from 20% to 4%, for example. Insome ducts, the perforations can define a flow surface porosity, theporosity ranging from 10% to 6%, for example.

In at least one embodiment, the depth of the plurality of cavities candefine a continuous distribution, a constant distribution, or a stepdistribution with at least one step. In at least one embodiment, thedepth of the plurality of cavities can define a constant distribution ora step distribution with at least one step. In at least one embodiment,the duct can be formed of titanium, titanium alloys, aluminum, aluminumalloys, stainless steel, or polymer. For some ducts, the duct caninclude a polymer. For some duct embodiments, the duct can be a variablegeometry with at least one high aspect ratio inlet or exit.

FIG. 1 illustrates a perspective top view of an aircraft 100, such as anunmanned aerial vehicle (UAV), according to an embodiment of the subjectdisclosure. In at least one embodiment, the UAV 100 includes a main bodyor fuselage 101, wings 102, and canards 103. The main body 101 definesan inlet 110. The inlet 110 leads into a flow path duct system of apropulsion system. The flow path duct system extends into and through atleast a portion of the UAV 100. The flow path duct system is describedherein.

Optionally, the UAV 100 can be sized, shaped, and configured differentlythan shown in FIG. 1 . For example, the UAV 100 may not include canards.As another example, the wings 102 can be disposed at locations that areforward from the wings 102 as shown. As another example, the UAV 100 maynot include wings. Instead, the UAV 100 can include one or morehelicopter-like rotors, for example.

FIG. 2 illustrates a front perspective view of an aircraft 100,according to an embodiment of the subject disclosure. The aircraft 100includes a propulsion system 212 that includes two engines 202, forexample, such as two turbofan or turbojet engines. Optionally, thepropulsion system 212 may include more engines 202 than shown. Theengines 202 are carried by wings 216 of the aircraft 100. In otherembodiments, the engines 202 are carried by a fuselage 218 and/or anempennage 220. The empennage 220 may also support horizontal stabilizers222 and a vertical stabilizer 224. The fuselage 218 of the aircraft 100defines an internal cabin, including a flight deck. The engines 202include flow path duct systems, such as described herein.

The aircraft 100 can be sized, shaped, and configured differently thanshown in FIG. 2 . The aircraft 100 shown in FIG. 1 is merely an example.

FIG. 3 illustrates a lateral perspective view of an engine 202,according to an embodiment of the subject disclosure. In at least oneembodiment, the engine 202 is a turbofan or turbojet engine having acase 300 that includes an engine inlet 314, which leads into a flow pathduct system, as described herein. The engine inlet 314 may include aleading edge 316 and an inner barrel section 320 located aft of theleading edge 316 of the engine inlet 314. The inner barrel section 320can provide a boundary surface or wall for directing airflow (not shown)entering the engine inlet 314 and passing through the engine 202. Theinner barrel section 320 can be located in relatively close proximity toone or more fan blades (not shown in FIG. 3 ). In at least oneembodiment, the inner barrel section 320 can also be configured to serveas an acoustic structure having a plurality of perforations in an innerface sheet of the inner barrel section 320 for absorbing noise generatedby the rotating fan blades and/or noise generated by the airflowentering the engine inlet 314 and passing through the engine 202. In atleast one embodiment, the inner barrel section 320 includes, and or canbe configured as, a flow path duct system, as described herein.

FIG. 4 illustrates a perspective internal view of a flow path ductsystem 400, according to an embodiment of the subject disclosure. FIG. 5illustrates a perspective external view of the flow path duct system 400with a backing surface removed to expose supports and resultingcavities, according to an embodiment of the subject disclosure.

Referring to FIGS. 4 and 5 , in at least one embodiment, the flow pathduct system 400 is within the UAV 100 shown in FIG. 1 . For example, theinlet 110, shown in FIG. 1 , leads into, or forms an inlet of, the flowpath duct system 400. In at least one other embodiment, the flow pathduct system 400 is within the engine 202 shown in FIGS. 2 and 3 . Forexample, the engine inlet 314, shown in FIG. 3 , leads into, or forms aninlet of, the flow path duct system 400.

The flow path duct system 400 provides a quiet propulsion flow pathsystem. The flow path duct system 400 includes an internal surface 428,which defines a flow surface 410. For example, a base 426 includes theinternal surface 428 that defines the flow surface 410. Fluid, forexample, air, travels over and along the flow surface 410. Supports 420extend opposite from the base 426, such as at edges 422 and an externalsurface. The supports 420 can include frames, beams, ribs, fins, walls,or the like.

The supports 420 define a plurality of cavities 421. For example, acavity 421 a is defined between a first support 420 a and a secondsupport 420 b. A cavity 421 b is defined between the second support 420b and a third support 420 c. The supports 420 can be sized and shapedthe same. The supports 420 can be upstanding fins, walls, beams, ribs,and/or or the like.

The flow path duct system 400 also includes a backing surface 430 and aplurality of perforations 440. For example, the backing surface 430 isdisposed over external portions of the supports 420, the cavities 421,and/or the perforations 440. The perforations 440 can be formed in thebase 426, for example. As an example, the supports 420 extend from thebase 426, which provides the flow surface 410. In at least oneembodiment, the supports 420 are or otherwise include fins 427 thatextend from the base 426. The cavities 421 are defined between the base426 and the fins 427. The perforations 440 are formed into and/orthrough the base 426. As such, a fluid flow path extends between thecavities 421, the perforations 440, and the internal volume 435 of theflow path duct system 400. The backing surface 430 can be a sheet, skin,or the like, disposed over the supports 420 and the cavities 421.

The cavities 421 extend from external surfaces of the base 426, oppositefrom the flow surface 410, thereby extending away from the internalvolume 435. The perforations 440 are formed in the base 426 and are influid communication with the internal volume 435. As such, the fluidflow path extends from the cavities 421, through the perforations 440 inthe base 426, and into the internal volume 435.

In at least one embodiment, the depth 423 of the cavities 421 isconstant throughout the flow path duct system 400. That is, thedistribution of depths 423 of the cavities 421 can be the samethroughout the flow path duct system 400. Optionally, the depths ofcertain cavities 421 can differ. In at least one embodiment, the flowpath duct system 400 shown in FIGS. 4 and 5 provides a monolithic,complex geometry inlet structure can be fabricated that provides soundattenuation.

In at least one embodiment, as shown in FIG. 5 , the supports 420include intersecting, beams, ribs, panels, walls, or fins 427 thatintersect to form a plurality of repeating cavities 421. The supports420 define outer boundaries for the cavities 421, which can have variousshapes and sizes.

In at least one embodiment, the flow path duct system 400 is for apropulsion system of an aircraft. The flow path duct system 400 includesthe base 426 defining the flow surface 410 (such as on an internalsurface 428). The base 426 includes the internal surface 428 and anexternal surface 432. A plurality of perforations 440 are formed throughthe base 426 between the internal surface 428 and the external surface432. The supports 420 define the cavities 421. The supports 420 extendoutwardly from the external surface 432 of the of the base 426. One ormore of the plurality of cavities 421 are in fluid communication withthe one or more of the plurality of perforations 440. The backingsurface 430 is secured to the plurality of supports 420. The supports420 are disposed between the base 426 and the backing surface 430. Oneor more of the plurality of cavities 421 are in fluid communication withan internal volume 435 defined by the internal surface 428 of the base426 through one or more of the plurality of perforations 440.

In at least one embodiment, the base 426, the supports 420, and thebacking surface 430 are integrally formed together as a monolithic,load-bearing structure. For example, the base 426, the supports 420, andthe backing surface 430 are additively manufactured together. That is,the flow path duct system 400, including the components thereof, areintegrally formed through an additive manufacturing process.

In at least one embodiment, each of the cavities 421 is in fluidcommunication with at least one the perforations 440, and/or vice versa.In at least one embodiment, cavities 421 and the perforations 440cooperate to provide a plurality of Helmholtz resonators.

FIG. 6 illustrates a transverse partial cross-sectional view of the flowpath duct system 400 having constant depth cavities, according to anembodiment of the subject disclosure. As shown in FIG. 6 , the flow pathduct system 400 can be an inlet 401. The depth (or height) 423 of thecavities 421 can be constant along a length 460 of the flow path ductsystem 400.

FIG. 7 illustrates a transverse partial cross-sectional view of the flowpath duct system 400 having constant depth cavities 421, according to anembodiment of the subject disclosure. As shown in FIG. 7 , the flow pathduct system 400 can be an outlet nozzle 403. Again, the depth (orheight) 423 of the cavities 421 can be constant along a length 462 ofthe flow path duct system 400.

Referring to FIGS. 6 and 7 , while the depths 423 of the cavities 421can be the same throughout the flow path duct system 400, the widths 429can differ. For example, a first set of cavities 421 can have a firstwidth that differs from a second set of cavities 421. Optionally, thewidth 429 of the cavities 421 can be the same throughout.

FIG. 8 illustrates transverse partial cross-sectional view of a flowpath duct system 400 having cavities 421 c and 421 d with a single stepdistribution in depth 423, or two constant depths, according to anembodiment of the subject disclosure. For example, a first set ofcavities 421 c has a depth 423 that differs from a depth 423 of a secondset of cavities 421 d. A step 425 defines a transition between the firstset of cavities 421 c and the second set of cavities 421 d. As shown,the depth 423 of the first set of cavities 421 c is greater than thedepth 423 of the second set of cavities 421 d. Optionally, the depth 423of the second set of cavities 421 d can be greater than the depth 423 ofthe first set of cavities 421 c.

FIG. 9 illustrates a transverse partial cross-sectional view of a flowpath duct system 400 having cavities 421 e, 421 f, and 421 g with adouble step distribution in depth, or three constant depths, accordingto an embodiment of the subject disclosure. For example, a first set ofcavities 421 e has a depth 423 that differs from a depth 423 of a secondset of cavities 421 f, which differs from a depth 423 of a third set ofcavities 421 g. A step 431 defines a transition between the first set ofcavities 421 e and the second set of cavities 421 f. A step 433 definesa transition between the second set of cavities 421 f and the third setof cavities 421 g. As shown, the depth 423 of the first set of cavities421 e is greater than the depth 423 of the second set of cavities 421 f.Further, the depth 423 of the second set of cavities 421 g is greaterthan the depth 423 of the third set of cavities 421 g. Optionally, thedepth 423 of the second set of cavities 421 f can be greater than thedepth 423 of the first set of cavities 421 e, and/or the depth 423 ofthe third set of cavities 421 g can be greater than the depth 423 of thesecond set of cavities 421 f.

Referring to FIGS. 4-9 , certain embodiments provide a flow path ductsystem 400, and a method of making the flow path duct system 400. In atleast one embodiment, the method includes additively manufacturing aduct geometry as a monolithic structure, in which the geometry includesthe flow surface 410, the supports 420 defining the plurality ofcavities 421 isolated from each other, and the backing surface 430. Inat least one embodiment, the supports 420 are between the flow surface410 and the backing surface 430.

In at least one embodiment, the flow path duct system 400, and themethod of forming the flow patch duct 400, also includes the pluralityof perforations 440. The perforations 440 are in fluid communicationwith one or more cavities 421. In at least one embodiment, the pluralityof perforations 440 can be added to the flow surface 410, as opposed toadding them during an additive manufacturing step.

As noted, the supports 420 are between the base 426 and the backingsurface 430. In at least one embodiment, the supports 420 can be joinedtogether. For example, the supports 420 can be fastened together. In atleast one embodiment, the flow surface 410, the supports 420, and thebacking surface 430 define the cavities 421, which are internal to theflow path duct system 400. The cavities 421 are isolated from oneanother. In at least one embodiment, the base 426, the supports 420, andthe backing surface 430 together form a monolithic, load bearingstructure. In at least one embodiment, the monolithic structure can beadditively manufactured. In at least one embodiment, the flow path ductsystem 400 can be a primary load bearing structure, thereby resulting inan integrated design with reduced part count and reduced complexity.

The base 426 includes a plurality of perforations 440. One or morecavities 421 are in fluid communication with an internal volume 435 ofthe flow path duct system 400 through the perforations 440. Theperforations 440 provide an acoustic flow path to the underlyingisolated cavities 421 to effectively attenuate sound energy. In at leastone embodiment, the cavities 421 and the perforations 440 together forma plurality of Helmholtz resonators that are configured to attenuatesound.

The perforations 440 can have a variety of sizes and shapes. Forexample, the perforations 440 can be formed as ellipses, circles,squares, rounded squares, diamonds, rounded diamonds, rectangles,rounded rectangles, parallelograms, rounded parallelograms, or acombination thereof. A rounded perforation 440 has junctions, edges, andthe like that are filleted to provide a smooth transition. In at leastone embodiment, the perforations 440 can be circular.

In at least one embodiment, the number of size of the perforations 440(for example, a surface area and volume of perforation) defines aporosity of the flow surface 410. For example, the porosity (that is,the total volume of open space within the flow path duct system 400), asdefined by the perforations 440, ranges from about 20% (for example,between 18%-22%), about 15% (for example, between 13%-17%), about 10%(for example, between 8%-12%), about 8% (for example, between 6%-10%),about 6% (for example, between 4%-8%), or about 5% (for example, between3%-7%), to about 4% (for example, between 2%-5%), or any combinationthereof. In at least one embodiment, the porosity ranges from about 10%to about 6%, or about 8%, for example.

In at least one embodiment, the plurality of cavities 421 define adistribution of shapes including triangles, diamonds, circles, hexagons(honeycomb), or a combination thereof. For example, as shown in FIG. 5 ,the cavities 421 have shapes 490 in the form of diamonds. In at leastone embodiment, the cavities 421 define a distribution of diamondshapes, as shown in FIG. 5 , for example. The supports 420 define theouter envelopes of the shapes of the cavities 421. As such, the supports420 provide load transmission and structural support for the flow pathduct systems 400, and define the envelopes of the cavities 421.

In at least one embodiment, the size and spacing of the perforations 440and the cavities 421 is tuned for tailored frequency attenuation usingmethods known in the art, for example noise propagation codes (oneexample being ACoustic TRANsmission (ACTRAN®)), or theoretical methodsdescribed in Wu et al., Noise Attenuation Performance of a HelmholtzResonator Array Consist of Several Periodic Parts, 17 Sensors 2029(2017). In at least one embodiment, the depth of cavities can be variedfor sound attenuation optimization. In some embodiments, the depths 423of the cavities 421 define a continuous distribution, a constantdistribution, a step distribution with at one step for example, onestep, two steps, or more).

In at least one embodiment, the material of the flow path duct system400 can vary depending on actual use and environmental conditions. Forexample, the flow path duct system 400 is formed of titanium, titaniumalloys, aluminum, aluminum alloys, stainless steel, one or morepolymers, and/or the like.

In at least one embodiment, the flow path duct system 400 includes avariable geometry. For example, the flow patch duct system 400 includesan inlet flow path, an exit, a nozzle, a partial flow path, and/or acomplete flow path. In at least one embodiment, at least one of theinlet (such as the inlet 401 shown in FIG. 6 ) or the exit (such as thenozzle outlet 403 shown in FIG. 7 ) includes a high aspect ratio. Theaspect ratio is defined as a ratio of width/height of the flow path ductsystem 400, with an aspect ratio greater than two (that is, the widthbeing at least twice the height) being a high aspect ratio for a flowpath duct system 400. In at least one embodiment, both the inlet 401 andnozzle outlet 402 have high aspect ratios.

While the fluid path duct systems 400 described herein can be monolithicin terms of the construction of the acoustic treatment and the loadbearing structure, the complete assembled flow path duct systems 400 asintegrated into a vehicle (such as an aircraft) can include severaldifferent monolithic duct geometry sections (for example, inlet, nozzle,upper half, lower half) as opposed to one large section due to additivemanufacturing and installation constraints.

In at least one embodiment, instead of additively manufacturing the flowsurface 410 with a plurality of perforations 440, different methods canbe used to form the perforations 440. For example, the perforations 440can be formed through drilling cutting, laser cutting, vaporization,ablation, chemical treatment, and/or the like.

As described herein, certain embodiments of the subject disclosureprovide a quiet propulsion flow path duct system 400, which includes theflow surface 410, a plurality of supports 420 defining a plurality ofcavities 421 isolated from each other, and a backing surface 430. Thesupports 420 are between the flow surface 410 and the backing surface430. For example, the supports 420 are sandwiched between the flowsurface 410 and the backing surface 430. The base 426 having the flowsurface 410 includes a plurality of perforations 440, such that at leastone underlying cavity 421 is in fluid communication with the internalvolume 435 through the perforations 440. In at least one embodiment, theflow surface 410, the supports 420, and the backing surface 430 togetherform a monolithic, load bearing structure.

FIG. 10 illustrates a flow chart of a method of forming a flow path ductsystem for a propulsion system of an aircraft, according to anembodiment of the subject disclosure. Referring to FIGS. 1-10 , themethod includes forming, at 500, a plurality of perforations 440 througha base 426 defining a flow surface 410 between an internal surface 428and an external surface 432; extending, at 502, a plurality of supports420 defining a plurality of cavities 421 from the external surface 432of the of the base 426; fluidly coupling, at 504, one or more of theplurality of cavities 421 with one or more of the plurality ofperforations 440, wherein said fluidly coupling 504 includes fluidlycoupling the one or more of the plurality of cavities 421 with aninternal volume 435 defined by the internal surface 428 of the base 426through the one or more of the plurality of perforations 440; andsecuring, at 506, a backing surface 430 to the plurality of supports420, wherein said securing 506 includes disposing the plurality ofsupports 420 between the base 426 and the backing surface 430.

In at least one embodiment, the method further includes integrallyforming the base 426, the plurality of supports 420, and the backingsurface 430 together as a monolithic, load-bearing structure. As afurther example, said integrally forming includes additivelymanufacturing the base 426, the plurality of supports 420, and thebacking surface 430 together.

In at least one embodiment, said fluidly coupling 504 includes fluidlycoupling each of the plurality of cavities 421 with at least one of theplurality of perforations 440.

In at least one embodiment, said forming 500 includes forming theplurality of perforations 440 to define a flow surface porosity withinthe base that ranges from 20% to 4%.

In at least one embodiment, the method includes forming the flow pathduct system 400 as one or both of an inlet or an outlet nozzle having ahigh aspect ratio.

It has been discovered that the embodiments of the flow path ductsystems 400 described herein reduce acoustic noise, as well as beingable to serve as a primary, load-bearing structure.

Further, the disclosure comprises embodiments according to the followingclauses:

-   -   Clause 1. A flow path duct system for a propulsion system of an        aircraft, the flow path duct system comprising:        -   a base defining a flow surface, wherein the base has an            internal surface and an external surface, wherein a            plurality of perforations are formed through the base            between the internal surface and the external surface;        -   a plurality of supports defining a plurality of cavities,            wherein the plurality of supports extend outwardly from the            external surface of the of the base, and wherein one or more            of the plurality of cavities are in fluid communication with            one or more of the plurality of perforations; and        -   a backing surface secured to the plurality of supports,        -   wherein the plurality of supports are disposed between the            base and the backing surface, and        -   wherein the one or more of the plurality of cavities are in            fluid communication with an internal volume defined by the            internal surface of the base through the one or more of the            plurality of perforations.    -   Clause 2. The flow path duct system of Clause 1, wherein the        base, the plurality of supports, and the backing surface are        integrally formed together as a monolithic, load-bearing        structure.    -   Clause 3. The flow path duct system of Clause 2, wherein the        base, the plurality of supports, and the backing surface are        additively manufactured together.    -   Clause 4. The flow path duct system of any of Clauses 1-3,        wherein each of the plurality of cavities is in fluid        communication with at least one of the plurality of        perforations.    -   Clause 5. The flow path duct system of Clause 4, wherein the        plurality of cavities and the plurality of perforations        cooperate to provide a plurality of Helmholtz resonators.    -   Clause 6. The flow path duct system of any of Clauses 1-5,        wherein the plurality of cavities are shaped as one or more of        triangles, diamonds, circles, or hexagons.    -   Clause 7. The flow path duct system of any of Clauses 1-6,        wherein the plurality of perforations are rounded.    -   Clause 8. The flow path duct system of any of Clauses 1-7,        wherein the plurality of perforations define a flow surface        porosity within the base that ranges from 20% to 4%.    -   Clause 9. The flow path duct system of any of Clauses 1-8,        wherein a depth of the plurality of cavities is the same.    -   Clause 10. The flow path duct system of any of Clauses 1-9,        wherein a depth of at least two of the plurality of cavities is        different.    -   Clause 11. The flow path duct system of any of Clauses 1-10,        further comprising one or both of an inlet or an outlet nozzle        having a high aspect ratio.    -   Clause 12. A method of forming a flow path duct system for a        propulsion system of an aircraft, the method comprising:        -   forming a plurality of perforations through a base defining            a flow surface between an internal surface and an external            surface;        -   extending a plurality of supports defining a plurality of            cavities from the external surface of the of the base;        -   fluidly coupling one or more of the plurality of cavities            with one or more of the plurality of perforations, wherein            said fluidly coupling comprises fluidly coupling the one or            more of the plurality of cavities with an internal volume            defined by the internal surface of the base through the one            or more of the plurality of perforations; and        -   securing a backing surface to the plurality of supports,            wherein said securing comprises disposing the plurality of            supports between the base and the backing surface.    -   Clause 13. The method of Clause 12, further comprising        integrally forming the base, the plurality of supports, and the        backing surface together as a monolithic, load-bearing        structure.    -   Clause 14. The method of Clauses 12 or 13, wherein said        integrally forming comprises additively manufacturing the base,        the plurality of supports, and the backing surface together.    -   Clause 15. The method of any of Clauses 12-14, wherein said        fluidly coupling comprises fluidly coupling each of the        plurality of cavities with at least one of the plurality of        perforations.    -   Clause 16. The method of any of Clauses 12-15, wherein said        forming comprises forming the plurality of perforations to        define a flow surface porosity within the base that ranges from        20% to 4%.    -   Clause 17. The method of any of Clauses 12-16, further        comprising forming the flow path duct system as one or both of        an inlet or an outlet nozzle having a high aspect ratio.    -   Clause 18. An aircraft comprising:        -   a propulsion system including a flow path duct system, the            flow path duct system comprising:            -   a base defining a flow surface, wherein the base has an                internal surface and an external surface, wherein a                plurality of perforations are formed through the base                between the internal surface and the external surface;            -   a plurality of supports defining a plurality of                cavities, wherein the plurality of supports extend                outwardly from the external surface of the of the base,                and wherein each of the plurality of cavities is in                fluid communication with at least one of the plurality                of perforations; and            -   a backing surface secured to the plurality of supports,            -   wherein the plurality of supports are disposed between                the base and the backing surface, and            -   wherein the plurality of cavities are in fluid                communication with an internal volume defined by the                internal surface of the base through the plurality of                perforations.    -   Clause 19. The aircraft of Clause 18, wherein the base, the        plurality of supports, and the backing surface are additively        manufactured together as a monolithic, load-bearing structure.    -   Clause 20. The aircraft of Clauses 18 or 19, wherein the        plurality of perforations define a flow surface porosity within        the base that ranges from 20% to 4%.

As described herein, embodiments of the present disclosure providesystems and methods for efficiently and effectively reducing noise inrelation to various components, such as an engine of aircraft. Further,embodiments of the present disclosure provide relatively simple systemsand methods for reducing noise with respect to aircraft, for example.

While various spatial and directional terms, such as top, bottom, lower,mid, lateral, horizontal, vertical, front and the like can be used todescribe embodiments of the subject disclosure, it is understood thatsuch terms are merely used with respect to the orientations shown in thedrawings. The orientations can be inverted, rotated, or otherwisechanged, such that an upper portion is a lower portion, and vice versa,horizontal becomes vertical, and the like.

As used herein, a structure, limitation, or element that is “configuredto” perform a task or operation is particularly structurally formed,constructed, or adapted in a manner corresponding to the task oroperation. For purposes of clarity and the avoidance of doubt, an objectthat is merely capable of being modified to perform the task oroperation is not “configured to” perform the task or operation as usedherein.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) can be used in combination witheach other. In addition, many modifications can be made to adapt aparticular situation or material to the teachings of the variousembodiments of the disclosure without departing from their scope. Whilethe dimensions and types of materials described herein are intended todefine the parameters of the various embodiments of the disclosure, theembodiments are by no means limiting and are exemplary embodiments. Manyother embodiments will be apparent to those of skill in the art uponreviewing the above description. The scope of the various embodiments ofthe disclosure should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. In the appended claims and the detailed descriptionherein, the terms “including” and “containing” are used as theplain-English equivalents of the term “comprising” and the term “inwhich” is used as the plain-English equivalents of the term “wherein.”Moreover, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects. Further, the limitations of the following claims are notwritten in means-plus-function format and are not intended to beinterpreted based on 35 U.S.C. § 112(f), unless and until such claimlimitations expressly use the phrase “means for” followed by a statementof function void of further structure.

This written description uses examples to disclose the variousembodiments of the disclosure, including the best mode, and also toenable any person skilled in the art to practice the various embodimentsof the disclosure, including making and using any devices or systems andperforming any incorporated methods. The patentable scope of the variousembodiments of the disclosure is defined by the claims, and can includeother examples that occur to those skilled in the art. Such otherexamples are intended to be within the scope of the claims if theexamples have structural elements that do not differ from the literallanguage of the claims, or if the examples include equivalent structuralelements with insubstantial differences from the literal language of theclaims.

What is claimed is:
 1. A flow path duct system for a propulsion systemof an aircraft, the flow path duct system comprising: a base defining aflow surface, wherein the base has an internal surface and an externalsurface, wherein a plurality of perforations are formed through the basebetween the internal surface and the external surface; a plurality ofsupports defining a plurality of cavities, wherein the plurality ofsupports extend outwardly from the external surface of the of the base,and wherein one or more of the plurality of cavities are in fluidcommunication with one or more of the plurality of perforations; and abacking surface secured to the plurality of supports, wherein theplurality of supports are disposed between the base and the backingsurface, and wherein the one or more of the plurality of cavities are influid communication with an internal volume defined by the internalsurface of the base through the one or more of the plurality ofperforations.
 2. The flow path duct system of claim 1, wherein the base,the plurality of supports, and the backing surface are integrally formedtogether as a monolithic, load-bearing structure.
 3. The flow path ductsystem of claim 2, wherein the base, the plurality of supports, and thebacking surface are additively manufactured together.
 4. The flow pathduct system of claim 1, wherein each of the plurality of cavities is influid communication with at least one of the plurality of perforations.5. The flow path duct system of claim 4, wherein the plurality ofcavities and the plurality of perforations cooperate to provide aplurality of Helmholtz resonators.
 6. The flow path duct system of claim1, wherein the plurality of cavities are shaped as one or more oftriangles, diamonds, circles, or hexagons.
 7. The flow path duct systemof claim 1, wherein the plurality of perforations are rounded.
 8. Theflow path duct system of claim 1, wherein the plurality of perforationsdefine a flow surface porosity within the base that ranges from 20% to4%.
 9. The flow path duct system of claim 1, wherein a depth of theplurality of cavities is the same.
 10. The flow path duct system ofclaim 1, wherein a depth of at least two of the plurality of cavities isdifferent.
 11. The flow path duct system of claim 1, further comprisingone or both of an inlet or an outlet nozzle having a high aspect ratio.12. A method of forming a flow path duct system for a propulsion systemof an aircraft, the method comprising: forming a plurality ofperforations through a base defining a flow surface between an internalsurface and an external surface; extending a plurality of supportsdefining a plurality of cavities from the external surface of the of thebase; fluidly coupling one or more of the plurality of cavities with oneor more of the plurality of perforations, wherein said fluidly couplingcomprises fluidly coupling the one or more of the plurality of cavitieswith an internal volume defined by the internal surface of the basethrough the one or more of the plurality of perforations; and securing abacking surface to the plurality of supports, wherein said securingcomprises disposing the plurality of supports between the base and thebacking surface.
 13. The method of claim 12, further comprisingintegrally forming the base, the plurality of supports, and the backingsurface together as a monolithic, load-bearing structure.
 14. The methodof claim 12, wherein said integrally forming comprises additivelymanufacturing the base, the plurality of supports, and the backingsurface together.
 15. The method of claim 12, wherein said fluidlycoupling comprises fluidly coupling each of the plurality of cavitieswith at least one of the plurality of perforations.
 16. The method ofclaim 12, wherein said forming comprises forming the plurality ofperforations to define a flow surface porosity within the base thatranges from 20% to 4%.
 17. The method of claim 12, further comprisingforming the flow path duct system as one or both of an inlet or anoutlet nozzle having a high aspect ratio.
 18. An aircraft comprising: apropulsion system including a flow path duct system, the flow path ductsystem comprising: a base defining a flow surface, wherein the base hasan internal surface and an external surface, wherein a plurality ofperforations are formed through the base between the internal surfaceand the external surface; a plurality of supports defining a pluralityof cavities, wherein the plurality of supports extend outwardly from theexternal surface of the of the base, and wherein each of the pluralityof cavities is in fluid communication with at least one of the pluralityof perforations; and a backing surface secured to the plurality ofsupports, wherein the plurality of supports are disposed between thebase and the backing surface, and wherein the plurality of cavities arein fluid communication with an internal volume defined by the internalsurface of the base through the plurality of perforations.
 19. Theaircraft of claim 18, wherein the base, the plurality of supports, andthe backing surface are additively manufactured together as amonolithic, load-bearing structure.
 20. The aircraft of claim 18,wherein the plurality of perforations define a flow surface porositywithin the base that ranges from 20% to 4%.